The present invention is directed to an external oil separator for a refrigeration compressor. There is a natural affinity between oil and refrigerants. As a result, the presence of refrigerant in the lubricating oil may cause outgassing and a failure of the lubricant while oil carried over with the refrigerant interferes with heat transfer and may remove excessive amounts of oil from the oil sump. As exemplified by U.S. Pat. No. 4,788,825, oil separators use an inertial/centrifugal separation by changing the direction of the flow path in conjunction with a coalescer. Because an external oil separator includes a sump, the lubricant may not be readily available for compressor lubrication when the compressor is started due to the draining of lubricant when the compressor is idle, the distance to the sump, the mechanism for supplying lubricant, the viscosity of the lubricant, etc.